This invention relates to a plasticized coal tar pitch derived from coal tar products. This invention also relates to a composition containing the plasticized coal tar pitch of this invention and crude oil bitumen. Additionally, this invention relates to the use of the plasticized coal tar pitch and composition of this invention for the production of binders, for example, for use in road construction. By means of this invention it is possible to prepare flexible coatings on roadways, wherein the coatings have improved deformation properties.
The use of soft pitch products having softening points below about 40.degree. C. are known for use in the production of binders, useful, for example, in road construction. These soft pitch products consist of a mixture of coal tar pitch having a softening point of 60.degree. to 80.degree. C. and a tar oil fraction consisting of tetranuclear aromatic substances or compositions containing such substances in essential quantity. The mixture of coal tar pitch and tar oil fraction is blended with crude oil bitumen (distilled bitumen) for the production of the binders. See, for example, German Pat. No. 1 009 338.
The following statement is made at column 1, line 50 et seq. of the German Patent: "The tar oil is to be free of substances which separate in a crystalline manner after mixing with the coal tar pitch. Therefore, an oil is used in which the components are in an eutectic equilibrium. If required, the oil may be cooled and any crystals forming can be removed by centrifuging."
The soft pitch products and binders known in the art have not proved to be entirely satisfactory. There exists a need in the art for a plasticized coal tar pitch and a composition containing the plasticized coal tar pitch and crude oil bitumen, wherein these substances are suitable for use in the preparation of flexible coatings for roadways, wherein the coatings have improved deformation properties and improved viscosity properties.